Generally, a ski boot has a thick sole of rigid plastic material combined with a hard boot body to hold a suitable slouch during a descent, and to maintain sole in parallel with a ski as soon as the toe portion is fixed into a binding on the ski or ski board.
Therefore, the ski boot is unsuitable for walking which requires bending the toe portion, and for climbing a slope with the ski.
In view of the above inconvenience of the known ski boot, the present inventor has suggested a flexible ski boot in Japanese Patent No. 1,662,495 (Kokai No. HEI-3-24,201) wherein the sole of the boot comprises a rigid toe portion provided with a locking means inwardly and a main heel portion provided with a receiving hole for the locking means, respectively, wherein both portions are connected flexibly by a hinge means arranged on the bottom surface and a soft elastic material between both portions, for walking, and which are locked releasably by the locking means to hold the sole parallel to the ski binding when the ski is in use. The connected portion, however, permits an invasion of water, snow, dust, etc., into the boot through a V-shaped groove formed naturally between the toe portion and main heel portion, even if the groove is filled with soft elastic material. There is also a danger of injury to the sole of the foot due to getting in both ends of the V-shaped groove, during walking.